Untersuchungen zu Resonant Commutated Pole Kommutierungszellen in Spannungs- und Stromzwischenkreis-Umrichtern

In the last years pulse-controlled inverters using Insulated Gate Bipolar Tran sistors (IGBTs) have reached an outstanding position in the field of motor control and energy distribution. The power losses of the IGBTs can be lowered by the use of resonant techniques also called soft switching techniques. Hence it is possible to reduce cooling efforts, to raise switching frequency or to increase efficiency. In most cases the aim is an one-to-one replacement of the hard swit ched inverter. The Auxiliary Resonant Commutated Pole Inverter (ARCPI) has become a promising candidate to reach this aim, however, even this topology has got some drawbacks, e.g. balancing problems with the capacitive voltage divider in the DC link. This thesis starts with an excursus in the technology of modern power semi conductors in consideration of silicon carbide as a new base material. Subse quently a review of the most important resonant converter structures follows including a proposal for a structured method for their classification. Theoretical and experimental analysis of a total of four Resonant Commuta ted Pole commutation cells is done. The starting point is the classic voltage fed ARCPI. Results achieved in an optimised test set-up of a 1MVA converter for a motor-generator of a flywheel storage system are summarised. The three-phase current source ARCPI only needs two auxiliary switches. Therefore and due to the reason, that its capacitive voltage divider is easily stabilised by connecting it to the star point of the load, this solution is particularly attractive. Hence a three-phase inverter is built and measured. A new commutation cell, the so called Resonant Commutated Twin Pole (RCTP) cell, is derived using the laws of network theory. Its functionality is proved in a single-phase setup connected to a current source. The more promising voltage fed RCTP cell is examined in a three-phase inverter. All phases are realised using different technologies. Power losses in hard and soft switched mode with and without silicon carbide diodes are directly compared to each other. The theses is concluded by an appraisal of the new concept and by an outlook to possible realisations.